An optical fiber includes a glass portion, a primary coating layer, and a secondary coating layer. In the optical fiber, a value of microbend loss characteristic factor F.sub.μBL_GO is 2.6 ([GPa.sup.−1.Math.μm.sup.−10.5.Math.dB/turn].Math.10.sup.−27) or less, when represented by
F.sub.μBL_GO=F.sub.μBL_G×F.sub.μBL_O
by using geometry microbend loss characteristic F.sub.μBL_G and optical microbend loss characteristic F.sub.μBL_O.

A fiber optic cable assembly includes an elongate housing, a plurality of fiber optic cables placed inside the housing and extending longitudinally, and acoustic isolating material placed inside the housing and extending longitudinally. The acoustic isolating material includes a plurality of outwardly radially extending arms extending from a center of the housing towards a circumference of the housing. The plurality of arms divides a space inside the housing into a plurality of acoustically isolated sections. Each acoustically isolated section extends longitudinally. Each acoustically isolated section includes at least one of the plurality of fiber optic cables. Each acoustically isolated section is acoustically insulated from remaining sections of the plurality of acoustically isolated sections. A surface of the acoustic isolating material of each acoustically isolated section is covered by acoustic reflective material.

The present disclosure includes: an optical fiber ribbon including a plurality of optical fibers having an outer diameter of 0.2 mm or less and a ribbon resin that integrates the plurality of optical fibers in a parallel state; and a coating resin that covers the optical fiber ribbon. The optical fiber ribbon is in an assembled form in which the plurality of optical fibers are assembled so that a length in an arrangement direction is shorter than that of a case where the optical fibers are arranged in a row, and the optical fiber ribbon is covered with the coating resin in the assembled form.

An optical fiber cable includes: a plurality of ribs formed along a longitudinal direction of a cable; and a slot core in which a slot grove for housing an optical fiber ribbon is formed between the ribs. In the slot groove, a plurality of optical fiber ribbons are bundled and a plurality of subunits whose periphery is wound with a bundle material are provided, and the bundle materials between the plurality of subunits are bonded to each other.

An optical fiber ribbon includes N pieces of optical fibers in a state of being disposed in parallel. At least some parts of the N pieces of optical fibers contact each other and are connected to each other by a resin; an outer diameter of the optical fiber is equal to or larger than 0.135 mm and equal to or smaller than 0.180 mm; a connection part connected by the resin or another resin and a non-connection part not connected by the resin or another resin are intermittently provided in a longitudinal direction between intermittently connected core wires of an optical fiber disposed at the Mth and an optical fiber disposed at the (M+1)th among the N pieces of optical fibers; the N is a multiple of 12; and the M is a multiple of 4.

A cable comprising: a plurality of optical fiber cores; and one or more optical fiber core wires including one or more of the optical fiber cores. Further, at least one of the optical fiber core wire is fixed at a plurality of positions in a longitudinal direction of the cable so as to achieve substantially no displacement in a cable radial direction, at least a pair of the optical fiber core wires are fixed in a plane perpendicular to the longitudinal direction of the cable so as to achieve substantially no displacement relative to each other, and sensing of a strain profile in the longitudinal direction of at least the pair of the optical fiber core wires leads to achievement of sensing of a shape of the cable in the longitudinal direction.

An optical fiber cable having a slot core which includes a plurality of ribs formed along a cable longitudinal direction and in which slot grooves for housing optical fibers are formed between the ribs. The optical fiber cable includes: subunits each of which is formed by bundling a plurality of intermittent-connection-type optical fiber ribbons in which a connection part where adjacent optical fibers are connected to each other and a non-connection part where adjacent optical fibers are not connected to each other are intermittently provided in the longitudinal direction among some or all of optical fibers; and a thin-skin-shaped tube having Young's modulus lower than Young's modulus of a material forming the slot core. The subunits are housed in the slot grooves, and among the subunits in the slot grooves, at least a subunit located at an outer peripheral part of the slot grooves is covered with the tube.

An optical fiber cable having a slot core which includes a plurality of ribs formed along a cable longitudinal direction and in which slot grooves for housing optical fibers are formed between the ribs. The optical fiber cable includes: subunits each of which is formed by bundling a plurality of intermittent-connection-type optical fiber ribbons in which a connection part where adjacent optical fibers are connected to each other and a non-connection part where adjacent optical fibers are not connected to each other are intermittently provided in the longitudinal direction among some or all of optical fibers; and a thin-skin-shaped tube having Young's modulus lower than Young's modulus of a material forming the slot core. The subunits are housed in the slot grooves, and among the subunits in the slot grooves, at least a subunit located at an outer peripheral part of the slot grooves is covered with the tube.

An optical fiber cable includes optical fiber ribbons, a slot rod and a cable jacket. The slot rod has slot grooves in which the optical fiber ribbons are housed. The cable jacket covers an outside of the slot rod. The optical fiber ribbons have, in a state in which optical fibers having an outer diameter of 0.22 mm or less are arranged in parallel, connecting portions at which adjacent ones of the optical fibers are connected to one another and non-connecting portions at which adjacent ones of the optical fibers are not connected to one another, which are provided intermittently in a longitudinal direction. A density of core number of the optical fibers included in the optical fiber cable is 4.8 cores/mm.sup.2 or more in a cross section of the optical fiber cable.

A fiber optic cable assembly includes an elongate housing, a plurality of fiber optic cables placed inside the housing and extending longitudinally, and acoustic isolating material placed inside the housing and extending longitudinally. The acoustic isolating material includes a plurality of outwardly radially extending arms extending from a center of the housing towards a circumference of the housing. The plurality of arms divides a space inside the housing into a plurality of acoustically isolated sections. Each acoustically isolated section extends longitudinally. Each acoustically isolated section includes at least one of the plurality of fiber optic cables. Each acoustically isolated section is acoustically insulated from remaining sections of the plurality of acoustically isolated sections. A surface of the acoustic isolating material of each acoustically isolated section is covered by acoustic reflective material.